HR: 0800h
AN: B11A-0060    [Abstracts]
TI: Molecular Trickery - is Riverine DOM Really That Degraded?
AU: * Hernes, P J
EM: pjhernes@ucdavis.edu
AF: University of California, One Shields Avenue, Davis, CA 95616, United States
AU: Robinson, A C
EM: acrobinson@ucdavis.edu
AF: University of California, One Shields Avenue, Davis, CA 95616, United States
AU: Aufdenkampe, A K
EM: aufdenkampe@stroudcenter.org
AF: Stroud Water Research Center, 970 Spencer Road, Avondale, PA 19311, United States
AB: In the global carbon cycle, less than 1% of the ~60 Pg C fixed by primary production in terrestrial environments each year survives complete remineralization to be exported by rivers to marine environments. Conventional wisdom suggests that this riverine organic matter must therefore be highly degraded, and molecular biomarkers indicate increasing degradation with decreasing size such that dissolved organic matter (DOM) is the most degraded fraction. Conversely, 14C ages of particulate organic matter are significantly older than DOM, and in fact, DOM ages are typically only 10-40 years. Our study of lignin fractionation during litter leaching and sorption of leachates to soils indicates that the degraded lignin signature of riverine DOM may be more an artifact of the processes of leaching and sorption than a true indicator of increased degradation.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0420 Biomolecular and chemical tracers
DE: 0428 Carbon cycling (4806)
DE: 0442 Estuarine and nearshore processes (4235)
DE: 1806 Chemistry of fresh water
SC: Biogeosciences [B]
MN: 2007 Fall Meeting